1. Field of the Invention
The present invention relates to a hydraulic system of a work machine with a hydraulically controlled implement.
2. Description of the Related Art
Conventionally, there has been known a work machine provided with a main pump for supplying operating oil to a hydraulic actuator built in a hydraulically controlled implement, and a sub-pump for increasing a flow rate of the operating oil supplied to the hydraulic actuator (see U.S. Pat. No. 7,017,674B). In this hydraulic system of the work machine, to an operating oil flow passage from the main pump to the hydraulic actuator is connected a boost flow oil passage for flowing operating oil from the sub-pump, to thereby increase an amount of the operating oil to the hydraulic actuator. The control of the operating oil from the sub-pump (whether or not the operating oil is allowed to flow in the boost flow oil passage) is performed through control valves (high-flow valve).
With respect to such a work machine, in the case where a hydraulically-driven mower or the like is used in which the hydraulic actuator of a boost type (large-volume type) is driven by increasing the amount of the operating oil (boosting the flow), a large-volume type hydraulic actuator (large-volume type attachment) is connected to a connector provided in an operating oil flow passage.
On the other hand, in the case where a bucket or the like is used in which the hydraulic actuator (standard type) is driven not by increasing the amount of the operating oil, a standard type hydraulic actuator (standard type attachment) is connected likewise to the connector.
In this situation, it is not preferable that the high-flow valve be switched to the boosting side when the hydraulic actuator connected to the connector is of the standard type, since the hydraulic actuator suffers an excessive load.
Therefore, it would be desirable to provide a hydraulic system of a work machine which allows the operating oil to appropriately flow in accordance with the type of the connected hydraulic actuator.